The treatment of unerupted teeth, primarily the maxillary canines, has always been a challenge to both the orthodontist and the oral surgeon. It has been recognized that the maxillary canine follows a more difficult and tortuous path of eruption than any other tooth. Because of this, normal eruption frequently does not occur and the canine becomes impacted in a labial or palatal position. In treating this problem, various methods have been tried with varying degrees of success.
A commonly employed technique is to band the impacted canine at the time of surgery. The major advantage is that after the surgical procedure the orthodontist has excellent control of the tooth, from the standpoint of both force and direction. Disadvantages include poor access, excessive bone removal, and difficulty in cementation.
Another popular technique is to expose the impacted canine surgically, removing both bone and soft tissue. The area is then packed with a dental cement or periodontal dressing, thus keeping the wound open and allowing the tooth to erupt passively. Once it is accessible, it is banded and brought into position. The main advantage of the technique is that it is less difficult for the surgeon, while the major disadvantage is that the final result may show gingival recession and incomplete bone formation around the tooth.
A third method is to expose the tooth surgically and attach a chain or wire to the crown with pins, bonding material, or ligature wire. Advantages include conservation of bone and adequate postoperative control. Disadvantages are surgical difficulty and destruction of tooth structure.
In using ligature wire surgical exposure of the tooth has been advocated. The surgical flap gives proper access for the surgeon, and the ligature wire is very small and kind to the tissues. Once the flap is resutured, the ligature wire leads the way toward the proper eruptive path. The resutured flap is critical to proper bone formation around the erupting tooth and to proper gingival contour in the final result. This method is not without its disadvantages. Often access for passing the ligature wire around the neck of the canine is limited, particularly in older children in whom the follicle around the crown is small.
The ligature wire ends are usually just pigtailed into one solid twisted wire, which leaves the orthodontist at a disadvantage in applying the significant pull on these impacted canines which is necessary to bring them in nicely. The orthodontist must try to fashion the wire into some sort of hook on which to tie. Usually this sort of homemade bent hook gives way and greatly reduces the force that can be delivered to the tooth. It also is very uncomfortable for the patient when the orthodontist forms a hook while the wire is attached to the tooth.
There are certain physiologic principles which should be adhered to if the final orthodontic result is to show normal alveolar crest bone and normal gingival contour around an impacted canine which has been brought into the mouth. Once the apex of the tooth has fully formed, the tooth has lost most of its eruptive force and must be actively moved into the mouth. The normal eruptive pathway of a canine, if it has nothing to block it, is such that when the incisal edge breaks the gingiva at the alveolar crest it is surrounded by healthy gingiva. All bone-forming tissues would be nicely intact.